Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
  • D21H11/18—Highly hydrated, swollen or fibrillatable fibres
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/30—Luminescent or fluorescent substances, e.g. for optical bleaching
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
  • C08L1/02—Cellulose; Modified cellulose
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/001—Modification of pulp properties
  • D21C9/002—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives
  • D21C9/005—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives organic compounds
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/001—Modification of pulp properties
  • D21C9/007—Modification of pulp properties by mechanical or physical means
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/02—Chemical or chemomechanical or chemothermomechanical pulp
  • D21H11/04—Kraft or sulfate pulp
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
  • D21H11/20—Chemically or biochemically modified fibres
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
  • D21H17/375—Poly(meth)acrylamide
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
  • D21H17/42—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups anionic
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/28—Colorants ; Pigments or opacifying agents
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
  • C08B11/00—Preparation of cellulose ethers
  • C08B11/02—Alkyl or cycloalkyl ethers
  • C08B11/04—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals
  • C08B11/14—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals with nitrogen-containing groups
  • C08B11/15—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals with nitrogen-containing groups with carbamoyl groups, i.e. -CO-NH2
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/14—Polymer mixtures characterised by other features containing polymeric additives characterised by shape
  • C08L2205/16—Fibres; Fibrils
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/54—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen
  • D21H17/55—Polyamides; Polyaminoamides; Polyester-amides

Definitions

• the present invention relates to a process for producing a composition comprising microfibrillated cellulose by mechanically treating cellulose fibres in the presence of anionic polyacrylamide.
• the invention further relates to a composition produced according to the process.
• Microfibrillated cellulose is a material made from wood cellulose fibres, where the individual microfibrils or microfibrillated aggregates have been partly or totally detached from each other. MFC is normally very thin ( ⁇ 20 nm) and the length is often between 100 nm to 1 ⁇ m.
• Microfibrillated cellulose can be produced in a number of different ways. It is possible to mechanically treat cellulose fibres so that microfibrils are formed. However, it is very energy consuming to for example, shred or refine untreated cellulose fibres in order to form microfibrillated cellulose and it is therefore not often used. Combination of mechanical and chemical treatment can also be used. Examples of chemicals that can be used are those that either modifies the cellulose fibers through a chemical reaction or those that modifies the cellulose fibers via e.g. grafting or sorption of chemicals onto/into the fibers. By introducing carboxylic acid groups onto/into the fibers or for example the use of TEMPO, which oxidizes the fibers, an improved fibrillation is obtained. However, the use of chemicals that oxidizes or introduces anionic groups might be limited due to legislation, costs or health / safety risks, which is particularly important in paperboard. This is due to legislation that prevents the use of these chemicals in for example food board or liquid packaging board
• OBA optical brightening agents
• microfibrillated cellulose is described in WO2011051882A1 .
• Cellulose fibers are mechanically treated in an extruder in order to form microfibrillated cellulose. It is also possible to add chemicals, e.g. CMC to the extruder in order to produce modified microfibrillated cellulose.
• chemicals e.g. CMC
• Another object of the present invention is to produce a composition comprising microfibrillated cellulose with high negative charge.
• the invention relates to a process for treating cellulose fibres which process comprises the steps of providing a slurry comprising cellulose fibers, adding anionic polyacrylamide (A-PAM) with high molar mass to the slurry in a first step, subjecting the slurry to a mechanical treatment in a second step thereby forming a composition comprising microfibrillated cellulose.
• A-PAM anionic polyacrylamide
• the molar mass of the A-PAM added is above 10 x 10 6 g/mol. It has been shown that A-PAM with a molar masse below 10 x 10 6 g/mol will have no or small effect of the fibrillation and runnability of the mechanical treatment of the cellulose fibers.
• the charge of the added A-PAM preferably is below -1,5 mekv/g. It has been shown that A-PAM with a negative charge of below -1,5 mekv/g further will improve the fibrillation of the cellulose fibers.
• the amount of A-PAM added to the slurry is preferably between 150-2500 g/t (grams per ton) of dried MFC.
• the needed amount of A-PAM added to the slurry depends on the mechanical treatment as well as on the cellulose fibers treated.
• the temperature of the slurry comprising fibers and A-PAM is preferably increased to above 50 °C.
• the electrolyte preferable has monovalent, divalent or multivalent cations, such as sodium sulphate or calcium chloride.
• the electrolyte concentration of the slurry is preferably between 0.0001-0.5 M.
• the desired concentration depends on the cellulose material as well as on the A-PAM used.
• the cellulose fibers in the slurry are preferably pre-treated before addition of anionic polyacrylamide.
• the pre-treatment can be mechanical, chemical and/or enzymatic.
• the slurry is preferably mechanically treated in a high shear mechanical equipment. It has been shown that the runnability of equipment that subjects the slurry comprising MFC and A-PAM to high shear rates, such as a fluidizer or a homogenizator, is improved when cellulose fibers are mixed with A-PAM before the mechanical treatment.
• the slurry preferably has a consistency of between 1-40% by weight during the mechanical treatment. Since the addition of anionic polyacrylamide will increase the charge of the fiber suspensions, the fibers tend to deflocculate which makes it possible to increase the consistency of the slurry and still be able to produce a composition comprising microfibrillated cellulose in an efficient way.
• the process may further comprise addition of anionic polyacrylamide (A-PAM) with high molar mass to the slurry in a third step and subjecting the slurry comprising fibers and A-PAM to a mechanical treatment in a fourth step thereby forming a composition comprising microfibrillated cellulose.
• A-PAM anionic polyacrylamide
• the present invention further relates to a composition comprising microfibrillated cellulose and A-PAM with high molar mass produced according to the process described above. Due to the addition of anionic polyacrylamide during the production of microfibrillated cellulose the produced composition comprising microfibrillated cellulose will show increased negative charge which will improve the stability of the composition.
• the microfibrillated cellulose is also known as nanocellulose. It is a material typically made from wood cellulose fibers, both from hardwood or softwood fibers. It can also be made from microbial sources, agricultural fibers such as wheat straw pulp, bamboo or other non-wood fiber sources. In microfibrillated cellulose the individual microfibrils have been partly or totally detached from each other. A microfibrillated cellulose fibril is normally very thin ( ⁇ 20 nm) and the length is often between 100 nm to 10 ⁇ m. However, the microfibrils may also be longer, for example between 10-200 ⁇ m, but even lengths of 2000 ⁇ m can be found due to wide length distribution. Fibers that has been fibrillated and which have microfibrils on the surface and microfibrils that are separated and located in a water phase of a slurry are included in the definition MFC.
• cellulose whiskers microcrystalline cellulose (MCC), microcellulose (MC), microdenomimated cellulose, nanocrystalline cellulose (NCC) or fibrillated regenerated cellulose fibers and particles are also included in the definition MFC.
• the fibrils may also be polymer coated fibrils, i.e. a modified fibril either chemically or physically.
• the invention relates to a process for treating cellulose fibres which process comprises the steps of providing a slurry comprising cellulose fibers, adding anionic polyacrylamide (A-PAM) to the slurry in a first step and subjecting the slurry comprising fibers and A-PAM to a mechanical treatment in a second step in which a composition comprising microfibrillated cellulose and A-PAM is formed.
• A-PAM anionic polyacrylamide
• A-PAM has been shown to increase the charge of the composition, to reduce the friction between the fibers as well as to reduce the friction between the mechanical equipment used and the fibers, which will make it easier to fibrillate the fibers and also to improve the runnability of the equipment. Furthermore, A-PAM is a very cost efficient chemical and it is non-toxic which makes it possible to use for food based packaging materials, such as in food board and liquid packaging board.
• Anionic polyacrylamide is added to the slurry comprising cellulose fibers and the anionic polyacrylamide is thereafter mixed with the slurry comprising cellulose fibers. It is preferred that the mixing is done for at least 2 minutes.
• the mixing of the cellulose fibers and the A-PAM is done in order to ensure that the components of the slurry are well dispersed before the mechanical treatment. It is possible to add the A-PAM by the use of high sped mixers, extruders or spraying equipment etc in order to ensure that the A-PAM and the cellulose fibers are well mixed. This is especially important if small amounts of A-PAM are added.
• cellulose fibers normally are of negative charge it is only expected that small amounts of the added anionic polyacrylamide are adsorbed by the fibers.
• the amount of A-PAM in free form in the slurry can be controlled. It may however be desirable to increase the amount of A-PAM being absorbed by the fibers. This can be done in many different ways, for example by adjusting the temperature, by addition of an electrolyte, by addition of fixating chemicals and/or by altering the pH of the slurry.
• the temperature of the slurry comprising fibers and A-PAM is preferably increased to above 50°C, preferably above 75 °C and even more preferred above 100 °C.
• the electrolyte preferable has monovalent, divalent or multivalent cations, such as sodium sulphate or calcium chloride.
• the electrolyte concentration of the slurry is preferably between 0.0001-0.5 M, preferably between 0.001-0.4 M, whereas the final concentration depends on the valency and type of the ions.
• the desired concentration depends on the cellulose material as well as on the A-PAM used.
• fixating chemical such as dye or optical brightening agent
• a fixating chemical it is possible to modify the added A-PAM in such a way that absorption of the A-PAM onto the fibers is increased.
• the molar mass of A-PAM is above 10 x 10 6 g/mol, preferably above 12 x 10 6 g/mol or even more preferred above 15 x 10 6 g/mol. It was surprisingly found that anionic polyacrylamide with a high molar mass improved the runnability of the mechanical treatment of fibers in order to produce MFC. It was expected that anionic polyacrylamide with short polymer chains, i.e. A-PAM with low molar mass, would work as a dispersion agent and thus improve the runnability whereas it was expected that anionic polyacrylamide with long polymer chains, i.e. A-PAM with high molar mass, would work as a flocculant and thus decrease the runnability. However, it was found that the A-PAM with long polymer chains, i.e. with a high molar mass, worked even better than A-PAM with short polymer chains when it was added to cellulose fibers which thereafter were mechanically treated.
• the A-PAM added to the slurry can be linear and/or branched. It is preferred to use A-PAM with long polymer chains. However, amounts of A-PAM with shorter polymer chains, i.e. with lower molar mass, may also be present thus providing a solution with polydisperse molar mass distribution or e.g. bimodal size distribution. If branched A-PAM is used, the polymer chains can be shorter but the molar mass of the branched A-PAM is still high. The molar mass of the added A-PAM can be determined by any known method. It also possible to use modified A-PAM, e.g. A-PAM that contains other functional groups such as amphoteric or hydrophobically modified A-PAM.
• modified A-PAM e.g. A-PAM that contains other functional groups such as amphoteric or hydrophobically modified A-PAM.
• amphoteric A-PAM such as copolymer type amphoteric A-PAM which comprises both anionic and cationic charges.
• the charge of the added A-PAM is preferably below -1,5 mekv/g. It has been shown that A-PAM with a negative charge further will improve the fibrillation of the cellulose fibers.
• the charge can be determined by any known method.
• the amount of A-PAM added to the slurry is preferably between 150-2500 g/t of dried MFC, preferably between 800-1500 g/t of dried MFC.
• the needed amount of A-PAM added to the slurry depends on the mechanical treatment as well as on the cellulose fibers of the slurry. However, depending of the end use of the composition comprising MFC and A-PAM higher dosage of A-PAM could be necessary. If the composition should be used for strength enhancement, amounts of between 5-50 kg/t, preferably between 5-15 kg/t could be used.
• the cellulose fibers in the slurry are preferably pre-treated before addition of anionic polyacrylamide.
• the pre-treatment can be mechanical, chemical and/or enzymatic. It may be more energy efficient to treat pre-treated fibers according to the invention.
• the slurry comprising cellulose fibers and A-PAM is preferably mechanically treated in a high shear rate mechanical equipment, e.g. a fluidizer, homogenizator, extruder, e.g. conical extruders, high shear refiner, high shear fibrilator e.g. cavitron rotor/stator system or any other equipment subjecting the slurry to high shear rates.
• a high shear rate mechanical equipment e.g. a fluidizer, homogenizator, extruder, e.g. conical extruders, high shear refiner, high shear fibrilator e.g. cavitron rotor/stator system or any other equipment subjecting the slurry to high shear rates.
• the nozzles or slots of the high shear rate mechanical equipment normally have a high tendency to be stopped up, i.e. they get blocked by the treated fibers.
• A-PAM additive of A-PAM to the slurry comprising the fibers to be treated in the high shear rate mechanical equipment reduces the tendency of blocking or clogging the nozzles and/or slots and the runnability of the high shear rate mechanical equipment is improved.
• mechanical equipment such as refiner, defibrator, beater, friction grinder, disperger or other known mechanical fibre treatment apparatus.
• the slurry preferably has a consistency of between 1-40% by weight, preferably between 1-5% by weight, during the mechanical treatment. Since the addition of anionic polyacrylamide will increase the charge of the fiber suspension, the fibers tend to deflocculate which makes it possible to increase the consistency of the slurry and still be able to produce a composition comprising microfibrillated cellulose in an efficient way. The consistency of the produced composition comprising microfibrillated cellulose will thus also have a higher consistency. It is thus possible to produce a composition comprising MFC with high consistency which will facilitate transportation of the composition to the site of usage.
• the process may further comprise addition of anionic polyacrylamide (A-PAM) with high molar mass to the slurry in a third step and subjecting the slurry comprising fibers and A-PAM to a mechanical treatment in a fourth step thereby forming a composition comprising microfibrillated cellulose.
• A-PAM anionic polyacrylamide
• A-PAM mechanically treat the slurry comprising cellulose fibers and A-PAM in more than two steps, e.g. three, four or more steps.
• the amount of A-PAM added in each step depends on the mechanical treatment, i.e. equipment used, conditions of the mechanical treatments as well on the fibers being treated.
• the total amount of A-PAM added to the slurry should be between 150-2500 g/t of dried MFC. It may be preferred to add a small amount of A-PAM in the first step before the first mechanical treatment followed by addition of a larger amount of A-PAM in the third step before the second mechanical treatment.
• the present invention further relates to a composition comprising microfibrillated cellulose and A-PAM with high molar mass produced according to the process described above. Due to the addition of anionic polyacrylamide during the production of microfibrillated cellulose the produced composition will have increased negative charge. The increase of negative charge of the composition comprising MFC will both give the composition a higher cationic demand and an improved retention in papermaking processes. The presence of A-PAM in the composition will also reduce the flocculation of the produced MFC which will improve the ability of the MFC to mix with other materials and additives.
• A-PAM is known to increase the dry strength of for example paper or board.
• MFC and A-PAM it is normally not easy to mix MFC and A-PAM before addition to, e.g. the wet end, of a paper or board machine.
• An advantage with the present invention is that it is possible to produce a stable composition comprising both MFC and A-PAM which thus also can be used as an additive to increase the strength of a paper or board.
• composition comprising MFC and A-PAM as a viscosity control additive in for example ketchup or cement.
• the viscosity properties of the MFC of the composition are more stable compared to MFC compositions with no A-PAM. This is due to that the A-PAM will work as a deflocculating agent of the microfibrils of MFC.
• composition according to the invention An advantage with the composition according to the invention is that the added A-PAM could be in free form in the composition, i.e. the microfibrillated cellulose of the composition has not adsorbed all of the added A-PAM, i.e. the MFC is not chemically modified. Consequently, it could be easier to get the MFC of the composition approved for example as a food additive.
• composition as a purification additive of waste waters. Furthermore, it could be possible to use the composition in any known end uses where MFC can be used where or A-PAM can be used.
• the cellulose fibres used in the process according to the invention are preferably fibres of kraft pulp, i.e. they have been treated according to the kraft process. However, other chemical pulps, mechanical pulps or chemi-mechanical pulps can also be used, one example is sulphite pulp.
• the fibres can also be bleached or unbleached.
• the cellulose fibres may be hardwood and/or softwood fibres. It is also possible to use fibers from agricultural materials or regenerated cellulose fibers.
• Pre-treated pulp with a consistency of 3% was used. Different kinds of anionic polyacrylamides in different amounts were added to the pulp slurry and thereafter subjected to mechanical treatment in a microfluidizer. As a reference sample, no A-PAM was added to the pulp slurry before it was treated in the microfluidizer.
• the fiber suspension was first pre-treated with enzymes and then the anionic polyacrylamide was added to the suspension and mixed for 10 minutes (31 000 revs). After mixing, the samples were run three times through the Microfluidizer M-110EH-30 (Microfluidics Corp.) using a 400 and a 200 um chambers in the two first runs and then a 200/100 chambers in the final third run.
• M-110EH-30 Microfluidics Corp.
• the chemicals used were different anionic polyacrylamides having different anionicity and molar masses (Fennopol A3092, Fennopol A302, and Fennopol A392, all products by Kemira).
• the runnability is here defined as a clogging tendency of the fludizer which thus limits the operation at higher solid contents.
• Table1 shows runnability tests in a microfluidizer with and without addition of different types of anionic polyacrylamide Sample Type of A-PAM Amount of A-PAM (g/t of dried MFC) Molar mass A-PAM (g/mol) Charge of A-PAM (mekv/g) Runnability Ref 0 Poor 1 A3092 400 3-6 x 10 6 -6 Poor 2 A302 150 >15 x 10 6 -1,8 Adequate 3 A302 400 >15 x 10 6 -1,8 Good 4 A302 800 >15 x 10 6 -1,8 Extremely Good 5 A392 150 >15 x 10 6 -5,5 Adequate 6 A392 400 >15 x 10 6 -5,5 Good 7 A392 800 >15 x 10 6 -5,5 Extremely Good
• the runnability of the microfluidizer was visually evaluated. Depending on the quantity of clogging of the nozzles of the microfluidizer, the runnability was graded as poor, adequate, good and extremely good. It can be seen from the test above that addition of A-PAM with high molar mass strongly improves the runnability of the microfluidizer.

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• Life Sciences & Earth Sciences (AREA)
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• Polymers & Plastics (AREA)
• General Chemical & Material Sciences (AREA)
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• Wood Science & Technology (AREA)
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• Biochemistry (AREA)
• Paper (AREA)
• Compositions Of Macromolecular Compounds (AREA)
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